1. Field of the Invention
The present invention relates to a communication network or system, and to a communication method in which a plurality of nodes use a plurality of signal channels in common. More particularly, the present invention relates to a channel (wavelength or the like) division mutiplexing network and the like which are extended, for example, by connecting a plurality of groups of nodes with each other.
2. Related Background Art
Conventionally, a tree-type network is generally known. In a network system, such as a tree-type, in which the system is constructed in a multi-stage manner, however, a control method for performing channel multiplexing communication has been unknown so far.
It is an object of the present invention to provide a communication network, a communication method in which a control channel is disposed between nodes and exchange nodes and channel assignment or selection of a vacant channel is conducted, using at least the control channel, to perform communication, and a node used therein.
It is another object of the present invention to provide a communication network and a communication method in which control channels are disposed in a parallel manner between nodes and each exchange node, the control channel is multiplexed with multiplexed communication channels such that the configuration of transmission lines is simplified, the channel assignment is effected by using the control channel and the multiplexed communication channels such that communication operation is simplified and the time required for establishing a series of communication channels, through which communication is performed between a signal transmitting node and a signal receiving node, is shortened, and to provide a node used therein.
The objects of the present invention are achieved by the following communication networks, communication methods, and nodes and exchange nodes used in those communication networks.
According to one aspect of the present invention, there is provided a communication network which includes: a plurality of groups of nodes, each of the node groups including at least a node; a plurality of exchange nodes, each of the exchange nodes being connected to each one of the node groups; a plurality of first transmission lines for connecting each of the node groups with each one of the exchange nodes; and at least a second transmission line for connecting the exchange nodes with each other, and in which the nodes are connected with each other through at least one of the exchange nodes by multiplexed communication channels for transmission of a data signal established in the first and second transmission lines, and the nodes are connected with the exchange nodes by the multiplexed communication channels and at least one control channel for transmission of a control signal.
More specifically, the following constructions are possible:
The nodes in each group are connected with each of the exchange nodes by the multiplexed communication channels and at least one control channel established in the first transmission line in a parallel manner, and one of the exchange nodes serves as a channel management node for selecting or assigning a using or vacant channel to be used, from the multiplexed communication channels (corresponding to a first embodiment described below).
There is further arranged a third transmission line for connecting the nodes and the exchange nodes with each other in a loop form, the nodes in each node group are connected with each one of the exchange nodes by the muliplexed communication channels in a parallel manner, the nodes and the exchange nodes are serially connected with each other by the control channel established in the third transmission line, and one of the nodes and the exchange nodes serves as a channel management node for selecting or assigning a using channel to be used, from the multiplexed communication channels (corresponding to a second embodiment described below).
The exchange node is constructed such that a using channel (i.e., the channel to be used from among the multiplexed communication channels) can be exchanged for another in the exchange node. The control channel serves to transmit the control signal including data of at least one of a signal transmission channel in which the data signal is transmitted from a transmitting node of the nodes, a signal receiving channel in which the data signal is transmitted to a receiving node of the nodes, and communication start information for informing that communication is to be started. The multiplexed communication channels serve to transmit the data signal including data of an address of a receiving node to which the data signal is to be transmitted (corresponding to a first embodiment described below).
Each of the nodes performs communication with the exchange node connected with that node through the control channel, and the nodes perform communication with each other through at least one selected or assigned using channel of the multiplexed communication channels (corresponding to a first embodiment described below).
Each of the nodes performs communication with the channel management node through the control channel in a loop form, and the nodes perform communication with each other through at least one selected or assigned using channel of the multiplexed communication channels (corresponding to a second embodiment described below).
Each of the nodes includes a communication control unit for performing communication of the control signal including data of at least one of a signal transmission channel in which the data signal is transmitted from a transmitting node of the nodes, a signal receiving channel in which the data signal is transmitted to a receiving node of the nodes, and communication start information for informing that communication is to be started, a unit for transmitting the data signal to at least one channel of the multiplexed communication channels and a unit for receiving the data signal transmitted through at least one channel of the multiplexed communication channels. Each of the exchange nodes includes a communication control unit for performing communication of the control signal including data of at least one of a signal transmission channel in which the data signal is transmitted from a transmitting node of the nodes, a signal receiving channel in which the data signal is transmitted to a receiving node of the nodes, and communication start information for informing that communication is to be started, with the nodes and the other exchange nodes connected with that exchange node, a unit for monitoring a situation of used channels of the multiplexed communication channels, input terminals, output terminals and a unit for connecting a signal input into the input terminal through the multiplexed communication channel to at least one of the output terminals (corresponding to a first embodiment described below).
Each of the exchange nodes includes a unit for performing communication of the control signal including data of at least one of a signal transmission channel in which the data signal is transmitted from a transmitting node of the nodes, a signal receiving channel in which the data signal is transmitted to a receiving node of the nodes, and communication start information, with the nodes and the other exchange nodes connected with that exchange node, a unit for monitoring a situation of used channels of the multiplexed communication channels, input terminals, output terminals, a unit for connecting a signal input into the input terminal through the multiplexed communication channel to at least one of the output terminals and an exchange unit for exchanging the using channel for another or for converting a signal transmitted through one of the multiplexed channels to a signal to be transmitted through another channel (corresponding to a first embodiment described below).
The channel management node includes a unit for performing communication of the control signal including data of at least one of a signal transmission channel in which the data signal is transmitted from a transmitting node of the nodes, a signal receiving channel in which the data signal is transmitted to a receiving node of the nodes, and communication start information, with the nodes and the other exchange nodes and a unit for monitoring a situation of used channels of the multiplexed communication channels (corresponding to a second embodiment described below).
The exchange node includes input terminals, output terminals, a unit for connecting a signal input into the input terminal through the multiplexed communication channel to at least one of the output terminals and an exchange unit for exchanging the using channel for another or for converting a signal transmitted through one of the multiplexed channels to a signal transmitted through another channel (corresponding to a second embodiment described below).
The transmission lines comprise light transmission lines, and the multiplexed channels comprise wavelength division multiplexed channels to establish a wavelength division multiplexing communication network. The exchange node exchanges a wavelength of a signal for another among the wavelength division multiplexed channels. The multiplexed communication channels are separated from the control channel, spatially or using a plurality of wavelengths assigned to the respective channels.
According to another aspect of the present invention, there is provided a communication method performed in the above-discussed communication networks, in which a transmitting node of the nodes transmits a communication demand or request to the exchange node connected with the transmitting node, using the control channel, the exchange node notifies the transmitting node of a vacant or assigned channel of the multiplexed communication channels, using the control channel, the transmitting node transmits a data signal including at least an address of a receiving node of the nodes through the notified vacant channel, the exchange node connected with the receiving node detects the address of the receiving node from the data signal, and the exchange node notifies the receiving node of a signal receiving vacant channel of the multiplexed communication channels, through which the data signal is to be transmitted from the exchange node to the receiving node, using the control channel, to establish a series of communication channels through which the data signal is transmitted from the transmitting node to the receiving node (corresponding to a first embodiment described below).
According to still another aspect of the present invention, there is provided a communication method performed in the above-discussed communication networks, in which a transmitting node of the nodes transmits a communication demand to the channel management node connected with the transmitting node, using the control channel, the channel management node notifies at least one of the transmitting node and a receiving node of the nodes of at least one vacant channel of the multiplexed communication channels, using the control channel, and the transmitting node transmits a data signal to the receiving node through the at least one notified vacant channel (corresponding mainly to a second embodiment described below). The channel management node may further notify the exchange node of a vacant channel of the multiplexed communication channels or a type of communication, using the control channel.
According to still another aspect of the present invention, there is provided a communication method performed in the above-discussed communication networks, in which a transmitting node of the nodes transmits a data signal including at least an address of a receiving node of the nodes to a pre-assigned channel of the multiplexed communication channels which is assigned to the transmitting node beforehand, the exchange node connected with the receiving node detects the address of the receiving node from the received data signal, and the exchange node connected to the receiving node notifies the receiving node of a signal receiving vacant channel of the multiplexed communication channels, through which the data signal is to be transmitted from the exchange node to the receiving node, using the control channel, to establish a series of communication channels through which the data signal is transmitted from the transmitting node to the receiving node (corresponding to a third embodiment described below).
According to still another aspect of the present invention, there is provided a communication method performed in the above-discussed communication networks, in which a transmitting node of the nodes transmits a communication demand to the exchange node connected with the transmitting node, using the control channel, the exchange node notifies the transmitting node of a vacant or assigned channel of the multiplexed communication channels, using the control channel, the transmitting node transmits a data signal including at least an address of a receiving node to the notified vacant channel, the exchange node connected with the receiving node detects the address of the receiving node from the data signal, and the exchange node relays the data signal to the receiving node through a pre-assigned channel of the multiplexed communication channels, which is assigned to the receiving node beforehand, to establish a series of communication channels through which the data signal is transmitted from the transmitting node to the receiving node (corresponding to a fourth embodiment described below).
According to still another aspect of the present invention, there is provided a communication method performed in the above-discussed communication networks, in which a transmitting node of the nodes transmits a communication demand to the exchange node connected with the transmitting node, using the control channel, the exchange node notifies the transmitting node of a vacant or assigned channel of the multiplexed communication channels, using the control channel, the exchange node selects or assigns a vacant channel of the multiplexed communication channels to the exchange node connected with a receiving node, the transmitting node transmits a data signal including at least an address of the receiving node to the notified vacant channel, the exchange node connected with the transmitting node relays the data signal to the selected vacant channel, the exchange node connected with the receiving node selects or assigns a vacant channel of the multiplexed communication channels to the receiving node, the exchange node detects the address of the receiving node, and the exchange node notifies the receiving node of the selected vacant channel to the receiving node, using the control channel, to establish a series of communication channels through which the data signal is transmitted from the transmitting node to the receiving node (corresponding to a first embodiment described below).
According to still another aspect of the present invention, there is provided a communication method performed in the above-discussed communication networks, in which a transmitting node of the nodes transmits a communication demand to the exchange node connected with the transmitting node, using the control channel, the exchange node selects or assigns a vacant channel of the multiplexed communication channels to the exchange node connected with a receiving node, the transmitting node transmits a data signal including at least an address of the receiving node to a pre-assigned channel of the multiplexed communication channels, the exchange node relays the data signal to the selected vacant channel to the exchange node connected with the receiving node, the exchange node connected with the receiving node selects a vacant channel of the multiplexed communication channels to the receiving node, the exchange node detects the address of the receiving node, and the exchange node notifies the receiving node of the selected vacant channel to the receiving node, using the control channel, to establish a series of channels through which communication is performed from the transmitting node to the receiving node (corresponding to a third embodiment described below).
According to still another aspect of the present invention, there is provided a communication method performed in the above-discussed communication networks, in which a transmitting node of the nodes transmits a communication demand to the exchange node connected with the transmitting node, using the control channel, the exchange node notifies the transmitting node of a vacant channel of the multiplexed communication channels, using the control channel, the exchange node selects a vacant channel of the multiplexed communication channels to the exchange node connected with the receiving node, the transmitting node transmits a data signal including at least an address of the receiving node to the assigned or assigned vacant channel, the exchange node relays the data signal to the selected vacant channel, the exchange node connected with the receiving node detects the address of the receiving node from the data signal, and the exchange node transmits the data signal to the receiving node through a pre-assigned channel of the multiplexed communication channels, which is assigned to the receiving node beforehand, to establish a series of channels through which communication is performed from the transmitting node to the receiving node (corresponding to a fourth embodiment).
According to still another aspect of the present invention, there is provided a communication method performed in the above-discussed communication networks, in which a transmitting node of the nodes transmits a communication demand to the exchange node connected with the transmitting node or the channel management node, using the control channel, the exchange node or the channel management node notifies the transmitting node of a vacant channel of the multiplexed communication channels, using the control channel, the exchange node connected to a receiving node or the channel management node notifies the receiving node of a signal receiving channel of the multiplexed communication channels, through which the data signal is to be transmitted from the exchange node to the receiving node, using the control channel, and the transmitting node transmits a data signal to the receiving node through the notified vacant channel to establish a series of channels through which communication is performed from the transmitting node to the receiving node.
More specifically, the following constructions are possible in the above communication methods:
The exchange node connected with the transmitting node transmits the signal including at least the address to the exchange node connected with the receiving node, through the vacant channel of the multiplexed communication channels, the exchange node connected with the receiving node detects the address of the receiving node from the signal and notifies the receiving node of the receiving channel, using the control channel, to establish the series of channels, the exchange node connected with the receiving node then returns the signal including the address to the exchange node connected with the transmitting node, through another vacant channel of the multiplexed communication channels, the exchange node connected with the transmitting node notifies the transmitting node of the return, using the control channel, and then the transmitting node stops the transmission of the signal including the address and starts to perform communication to the receiving node (corresponding to a first embodiment described below).
When communication is performed between the nodes connected with the same exchange node, the transmitting node transmits the communication demand to the exchange node connected with the transmitting node, using the control channel, the exchange node notifies each of the transmitting node and the receiving node of each vacant channel of the multiplexed communication channels, using each control channel, the transmitting node transmits the data signal to the notified vacant channel, the exchange node relays the data signal to the receiving node, and the receiving node receives the data signal through the notified vacant channel (corresponding to a first embodiment described below).
When communication is performed between the nodes connected with the same exchange node, the transmitting node transmits the communication demand to the exchange node connected with the transmitting node, using the control channel, the exchange node notifies the receiving node of the receiving channel, using the control channel, the transmitting node transmits the data signal to the pre-assigned channel, the exchange node relays the data signal to the receiving node, and the receiving node receives the data signal through the notified receiving channel (corresponding to a third embodiment described below).
When communication is performed between the nodes connected with the same exchange node, the transmitting node transmits the communication demand to the exchange node connected with the transmitting node, using the control channel, the exchange node notifies the transmitting node of communication allowance, using the control channel, only when the receiving node is not in communication with another node, the transmitting node transmits the data signal to the pre-assigned channel of the receiving node, the exchange node relays the data signal to the receiving node, and the receiving node receives the data signal through the pre-assigned receiving channel (corresponding to a fourth embodiment described below).
The signal including the address of the receiving node may be a repetitive signal.
These advantages and others will be more readily understood in connection with the following detailed description of the preferred embodiments in conjunction with the drawings.